I believe this article on Salesforce Documentation should help you understand about VisualForce Email Template creation and live preview
Basically you just need to go to
- Administer \ Communication Templates \ Email Templates,
- then Click New Template button.
- Choose Visualforce and click Next button.
- Setup parameters like folder to store it, name, unique name, email subject, Recipient type, Related to type and click Save button.
=> voilà: you already see you live preview saying:
Congratulations!
This is your new Visualforce Email Template.
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To show email template preview in another page, you may need to have controller property like this:
public String templateBodyPreview { get {
EmailTemplate et = [ select id, name, body, subject, HTMLValue from EmailTemplate where name = 'test' ]
return 'Subject: ' + et.subject + '<br/>\r\nBody preview:' + et.body;
} private set; }
and in your visualforce page you can reference this property like
{!templateBodyPreview}